Cheap(!) Digital Storage Oscilloscope (DSO), Colour, 200MHz

Okay, I'm getting one! I found these links on eBay:

• OWON PDS5022S, 25MHz, 6K buffer, $369, Chinese.
• OWON PDS6062T, 100MHz, 6K buffer, $649, Chinese.
• Rigol 5102CAE 100Mhz, 4K buffer, $799, Chinese.
• Welec W2022A, 200MHz, 16K buffer, $674, UK/DE.

All of these units have large, colour LCD displays, two 1X/10X probes, and USB-to-PC connections for printing/analysis. These are modern, lightweight, standalone, digital storage scopes.

The OWON models may have an "S" or a "T" suffix on the model number. The "S" indicates a DSTN LCD, whereas a "T" means it has the faster/better TFT style of LCD display.

The Welec model includes free DHL delivery in the purchase price. Some OWON sellers also include free (air mail?) shipping in the purchase price, others want $35 extra.

The Welec is also made in 100Mhz, and 4-channel versions, though I didn't see any of those actually offered for sale anywhere.

I've ordered the Welec W2022A unit for my use here -- 200Mhz (1Gs/sec) should be good enough bandwidth for finding glitches and the like.

Cheers

Shipped it today, so now we'll find out how long DHL Economic shipping takes -- the more expensive express is usually overnight, but this method is reputed to take a week or two.

Oh, and the name Welec is apparently a contraction of Wittig Electronics GmbH, aka. Wittig Technologies, and appears to be owned/operated by three brothers in Germany. It's probably no larger than the empeg team from the early days of the Mk1.

EDIT: Heh.. and the first Wittig product was apparently the pen-style "scope probe" I linked to at the top of this thread, now discontinued.

Cheers

Mmm.. this week's price is $75 less (and cheaper in EU currency as well).

Cheers

It arrived here an hour ago, and I've plugged it in and played with it a bit since then.

• GUI responsiveness is slow to non-existent (EDIT: that's not entirely fair -- see further postings below)
• 1-3 seconds from button press/release to screen responding.
• Works fine as a basic digital oscilloscope.
• The included probes do not have very good clip-tips, nice pins though.
• No documentation on how to adjust 2 of the three adjustments on the probes.
• Oscilloscope features, specifically the FFT/Math functions, differ from descriptions in the Users Guide.
• many some illustrated features appear to be missing.

I hope to establish a dialog with the makers to find out about the missing features, and might end up shipping it back to them for a refund.

Cheers

Well, none of the email links from their web site actually function (mis-configured or out of date), but the email for the original eBay seller (Michael Wittig) works.

He's put me in touch with Thomas Wittig, who appears to be the software techie at least. Like I said at the outset, I think it's just a three man company.



So that's a good sign: they do respond (and quickly) to email.
And they do update their firmware -- most recently just a few weeks ago.

Apart from the missing FFT extensions (useful) and Roll mode (not useful), the rest appears to be as advertised.

And as long as Math and Quick Meas. are both turned off, the scope actually is fairly responsive after all. The manual does warn that turning them on will slow it down.. they just don't say how much.

More as I explore more..

Cheers

I'm having trouble finding high frequency signals to test the 200Mhz end of the scale with.

Here are some screen snaps of the scope showing a column address strobe (CAS) line from a Mk2a. Note that my ground clip was simply on the empeg chassis -- nowhere near the RAM chips.

The screen is much better than it looks in the photographs below, which suffer from some kind of moire interaction with my camera's bayer matrix sensor.

Lovely little "square waves", with a fair amount of ringing:

The screens look nice on that.

When you go in on the timebase, what happens to the trigger position?

I use a Tektronix TDS220 at work which can be utterly infuriating when you change the timebase, it moves the trigger position. Consequently, if the trigger position is off centre, by the time you're down to nanoseconds the bloody cursor is milliseconds "off the screen", and the only way to bring it back on screen is to go back up the timebase and then move the trigger position into the centre before going back to nanoseconds.

Wonder if there's any vids of your scope working? With the "slow" options off, what's the response like?

I could do with a scope at home.

Mmmm.. the software is slightly flakey, which I expected at this price point. Mostly it works rather well.

But with a captured waveform, and acquisitions OFF, one cannot zoom the waveform vertically. Horizontal zoom works, but not vertical zoom.

Also, when horizontal zoom is set at 50, 20, or 10ns/div, the horizontal scrolling no longer functions.

I think both of those are bugs, and I've emailed Thomas about them.

Cheers

Heh.. I really haven't figured that out. The display just seems to jump around with no pattern/algorithm that I can recognize. At the moment, it's useless to me for zooming in on anything other than a repetitive waveform, unless I can capture it again at the higher zoom level.

I've got to read through the documentation again, and figure out what all of the little on-screen indicators represent, and then figure out what's buggy and what isn't.

Cheers

To be honest, the only buttons I ever really touch on the textronix are Timebase, Trigger position and aquisition mode (single, continous). Other than that, I don't really touch any other buttons on it.

The thing that I could really do with is being able to capture waveforms (screenshots) onto the PC, the tektronix can do this but it requires an plug in module which we don't have.

As you say, it's substantially cheaper than anything around it, even if only the basic oscilloscope functions work then it'd probably be a winner for me.

I keep looking at the bitscope year in year out, but everytime I look at it I just think "junk". Even doing "hobby" stuff at home, it'd be severely limiting.

It'll be interesting to hear your thoughts on it after a week or so of working with it.

I actually prefer that (we have a TDS210, 220 and I think a 224). I'm quite used to moving the trigger point to the centre if I want to zoom on it. I just zoom on the centre of the screen rather than the trigger.

I loaded the PC software into VMware (under Linux), to see if it was any good.

Well, it has a fancy GUI to remote-control the scope over USB. The remote control does function, but the remote display in the GUI doesn't work.

The only feature that does seem to work is the Quick Print button on the front of the scope -- it sends a scrollable waveform image to the PC, which can then be saved and/or viewed there.

But the PC cannot zoom the waveform -- horizontal scrolling only.

Here's a saved waveform below. This was saved as a 72KByte JPG, so I opened and resaved it as a 2.6KByte PNG file (without resizing.. they just muffed the JPG, I figure).

The image has no grid lines, so it's not terribly useful. But the Print button in their software can include the grid lines for printouts. Perhaps I should try printing to a file to get them?

The actual image shows Hijack reading the current temperature from the empeg's ds1821 temperature sensor chip over a one-wire bus.

First Hijack pulls the DQ line low for a minimum of 480us, then tristates it again. The chip waits 15-60us, then pulses the line low to indicate presence. Hijack then strobes out the command, 0xAA in this case. The chip then responds with the current temperature reading.

That signal in the most recent dump seems pretty noisy.

Possibly that's due to only grounding to the empeg chassis. Is it still in this case?.

I was still using the chassis for that capture, but just now I did it again, with the ground lead clipped to the chassis screw that is less than 1cm from the trace I was probing. Same result.

Cheers

There are no JPEG artifacts in that image, which would suggest the JPEG "quality" was turned waaay up. JPEG becomes very unoptimal at those levels. JPEG is just a terribly poor choice for high contrast images.

Maybe the empeg is noisy. I would think it is though. Very hard to tell unless you have another CRO nearby to compare with.

Freaky. I've done a lot of 1 wire stuff over the past year, including the ds1821, various battery monitors and the SHA-1 iButtons for secure applications!

The processor I that I generally use (AT91SAM7S256) has the option to enable open drain on every IO pin, which is uber-handy for 1 wire. Just use the normal UART but open drain the TX and tie TX/RX together and you lose all the timing overheard by getting the uart to do it all for you!

Sounds like a handy chip, that. I suppose the SA1100 might be able to do something similar, if it wasn't already using all of the internal UARTs for other purposes!

Cheers

Oh, it is very acceptably quick when running as an ordinary scope, with the measurements and math (FFT) turned off. And even with measurements on, it's not bad. But turn on the math, and it gets slow, and with both on, it gets very slow.

I may put up a short video of it -- I think my tiny digicam can do that, though I don't know what format it makes.

I'm thinking of creating a somewhat detailed review page for this scope, since there's nothing else out there on it yet.

And I've decided to keep it. I do need a scope that's fast enough for digital work. Even with all of the current flaws, there's nothing else out there, at double the price, that can do 200Mhz better than this one.

Right now, it's a great regular oscilloscope, with the crucial added capability of freezing the display (and saving/printing it). As a storage scope it has issues: scrolling / zooming within the frozen display works some of the time, not others. The Wittigs have this to say about the scroll/zoom quirkiness:

We have been informed already that these have to be repaired in the next version ... I have forwarded this mail to the developers. Will inform you when the firmware release become available soon.

So it might get fixed, or at least made more usable. Either of which I would consider a bonus. But even as-is, it's a pretty good scope for the cash.

Cheers!

Oh.. I should also note: two hot pixels on the display, for anyone who is super fussy about such things. I only notice them during the 10-second startup sequence. Yes, it boots up faster than most empegs!

Cheers

It's probably just circuit noise in the empeg. But perhaps you have a fast enough scope to take a similar sample there?

This was just a Mk2a, with latest Hijack, plugged into (60Hz) mains. Test probe on pin-1 of the sensor chip, which is hidden underneath the display ribbon cable.

I'm thinking that we only see the noise because the scope samples at 1 gs/sec. A slow scope might miss most of those glitches. Does that make any sense?

Cheers

The Welec buttons themselves are a very appealing feature of this rig. These are soft, translucent silicone things. The oval shaped ones are backlit by coloured LEDs when active, and they sometimes even change colour: Eg. green/red for running/stopped on the Run/Stop button).

Great visual feedback that way. There are not too many buttons, and they use differing shapes/sizes/colours to facilitate navigation among them.

EDIT: The scroll knobs, on the other hand.. are little clicky rotary encoders, with a fairly low speed limit. Nothing like the scroll wheel on the Tek scopes.

My little digicam seems to record in .avi format. I'm attempting to upload a video to youtube now. It's BIG, though, so this'll take a couple of hours.

Or quite possibly much longer than that.

Here's my YouTube video showing the scope.

Cheers

The CAS line photos from earlier in this thread, didn't show an excess of noise -- just obvious ringing on those. But still.. now you've got me wondering about things.

So I clipped the ground clip onto the probe end, which should result in a rather quiet signal, and still saw noise.

Pretty much identical to the noise background that is present when no probes are connected, shown below. It's about a full vertical div of random noise at the highest vertical resolution, which is 10mV/div for 1:1 probes, or 100mV/div for 10:1 probes.

I don't have another scope to compare with here. Is this worth fretting about? (10mV/div x 10ns/div).

No, this cannot be good. Time to email the Wittigs again.

Hi,

A good test is to direct connect the 1kHz Calibration signal BNC to channel 1 BNC (a BNC to BNC cable) and see what the waveform looks like. You might need to use a coax T and a terminator.

This will give us a better idea of how much noise is present in the input amplifiers and ADC.

Look at several divisions (at least 4) at 1ms rate. look for similar noise on the top and bottom as shown in the picture above. Then go to the fastest speed that allows a rise time to start at the far left graticule and end near the middle (5th) graticule. Check the edge for non-monotonicity (the edge rises and then is stepped or falls, then rises again. There also should not be Overshoot (the ringing you see in your video).

If you see any of these anomolies, you might need to set the input impedance to 50 Ohm. Some scopes will only allow 5 Volt maximum input voltage though, make sure it will handle it. There should be NO waveform anomolies with the 50 Ohm termination.

Clipping the probe ground to the probe tip is a good way to sample the Electromagnetic Environment around a measurement area. You would be surprised what some debug environments look like. It forms a single turn loop probe (similar method as an EMI sniffer probe).

The inductance of the probe ground is really most of overshoot you see in your waveforms (it had better be). The best way to view waveforms is at the receive side and to use a short ground. The smaller the loop area - hence inductance - the more waveform fidelity you will see. If it has a ground ring near the probe tip, get a small spring that fits around the ring and bend one or 2 turns out and shape it for use as a ground for probing. You can see the difference easily by probing activity on the 74LVX74 chip pin 5, 6, 8 or 9 with the probe tip and use the spring ground you made to connect to pin 7. Capture the waveform slow sweep speeds and the fastest that will provide 5 divisions, save it. Then probe using the pin (pin 5, 6, 8, or 9) and use the long ground wire supplied with the probe. You should see all of overshoot go away with the short spring ground and it should return with the long ground.

If you want to see a higher bandwidth signal, the Empeg has some 74LVX and RAM parts that will exceed the bandwidth of the oscilloscope.

Be very careful probing not to short pins.

Ross

Well, the spring-clip ground pins (included with the probes) help a little, compared with the alligator clip grounds (also included).

But I really cannot tell if this is just a super-sensitive scope, or if it's got a large inherent noise floor.

When switching the vertical capture resolutions, they seem to be using mechanical relays internally to switch portions of their amplifier circuit in/out.

There seem to be three vertical amplifier ranges: 100mV, 200mV, 500mV, and then, *click* 1V, 2V, 5V, and then *click* 10V, 20V, 50V. The cleanest signals, by quite a bit, are at the settings at the top end of each range, just before a *click*: 500mV and 5V.

The signal gets less noisy on the lower ranges. Eg. On the 1V range, the noise spread is often about 0.3Volts.. but zoom down to the *click* 500mV range, and the noise spread is now contained within a (approx) 150mV range.

Here's a capture off of pin-8 of one of the 74vsx04 chips, first with the spring ground tip on pin-7, and again with just the alligator clip many inches away on the empeg chassis.

EDIT: Well, that was interesting.. my CF-USB reader (for transferring photos) just tried to self-destruct -- it got *very* hot, and the chip markings inside the reader have blackened.. Switching back to the old reader now..

Cheers

Mmm.. turning off the overhead work lamp makes a noticeable difference -- it seems to account for perhaps half the noise I'm seeing on some things.

Still seems excessive to me, but what do I know?

Now I've got a 5.6VDC battery pack -- four NiMH cells in series. Aligator ground clip on one end, probe tip on the other. On the 1V/div scale, it shows a noise level of 456mV on the *DC* signal.

Which is pretty much the same noise floor it "sees" without anything connected to the probe inputs.

So now I'll skip the battery, unplug all probe leads, and just let the scope measure ambient noise with no leads plugged in, and the input set to 1:1:

Peak-to-Peak measurements of the "signal"

625-625mV at 5V/div.
667-833mV at 2V/div.
458-500mV at 1V/div.
*click*
62.5-62.5mV at 500mV/div.
66.7-83.3mV at 200mV/div.
41.7-54.2mV at 100mV/div.
*click*
6.25-8.33mV at 50mV/div.
6.67-8.33mV at 20mV/div.
5.00-7.08mV at 10mV/div.

I wonder if all of this is due to the simple plastic case that this thing is wrapped in?

Meanwhile, confirmation of my observation as to which mV/div settings exhibit the lowest noise:
The first bit about the VGA is irrelevant. But I wonder if a Tek TDS2000 really is this noisy. Anyone got one? Connect a AA battery to it, and check the noise level at 500mV/div.

??

Humn. Something I remember is that all our scopes are connected to mains with plugs without an earth pin.

Trying to avoid shorting out circuits with the test/ground leads, I bet.

??

We have a number of Tek oscopes at work. I don't know what models they are, but I bet they're quite high end. (We design chips that run at very high frequencies.) Regardless, I'll try that out on Monday with one (or more) of the scopes and let you know. Remind me, though. I'm almost certain to forget.

Hi,

If I have time, I will get some waveforms for you too. I have an HP 250 MHz 1GS/s Digital, aa HP 400 MHz 1GS/s Digital, 350 MHz Tek 485, HP 1GHz Digital, and if I have time I might get our my Tek 7104 1GHz Analog.

Ross

Thanks, guys.

I'm mainly interested in results from scopes that cost less than $2000 or so, but a higher quality one or two would be fun as well.

Really, it's been so long since I had a scope, that all I can remember are smooth lines on them. And this scope never has smooth lines, so I don't know whether this is a problem or not.

Cheers

I can tell you now that the screens you've posted largely don't look ridiculously noisy.

I've got a TDS220 on my desk at work, if nobody else has managed to help by monday (and if I remember!) I'll have a look for you.

I think we have a TDS2000 in the Singapore office (where I am now). I'll have a look on Monday (also).

You are possibly starting to see the resolution of the AD converter coming in to play. Typically only 8 or 10 bits (i.e. the VGA resolution actually shows less detail with a 10 bit converter).

You mentioned connecting "nothing" to the probe inputs. That will pick up all sorts of noise and junk. You should always have something connected (even if it's tied to the ground clip which will still act as a loop antenna like Ross mentions).

That 1kHz test signal did look a bit noisy to me though.

Our company had a high end LeCroy scope (about $25000), and we noticed that the probes picked up noise from the scope display. I wouldn't be surprised if the probes were picking up noise from the lamp.

I wonder about that. The scope has 8-bit A-to-D, but how linear is that?

On the 480 pixel tall display, that's perhaps 2-pixels per A-to-D bit of resolution, assuming they map the A-to-D range to the height of the screen. Possibly a bad assumption, but the "noise" is more than 2-pixels worth.

Cheers

Sorry Mark, didn't get a chance to look today. Was really busy and tired because I spent from 1am to 4am catching an escaped hamster that had eat through its "hamster home" - otherwise there would have been tears!

Humn, not just that but what about the accuracy of the A/D (lsb)?

Ahh.. so that would give us +- 4 vertical pixels, but still not enough.

It is within their published specifications, I guess. Those appear to tolerate a 300mV variation on the 5V/div scale, which is pretty much what I'm seeing.

Now where did I think I read that?

Ahh.. their spec says Vertical Accuracy +/- 3%. What I visually observe here is a +/- 150mV (a 300mV noise range) when looking at a +5V signal:

(0.150V / 5.000V) = 3% exactly.

Now we just need to find the spec on a cheap Tek brand scope to compare with this.

Okay, found it here.

The TDS2000 series specifies DC Vertical Accuracy +3% on all models.

That's slightly different: plus 3%, not plus/minus 3%. But close enough for the price, I suppose!

Odd. The 2005 PDF datasheet for my TDS1002 has +/- 3% for the TDS1000 and TDS2000 series.

Ah. Nevermind. The TDS1000B is newer and has a USB port.

Your 1KHz test signal is still pretty noisy but if its within the accuracy range specified then I guess its normal.

Here are two screencaps of one of our oscilloscopes here, a Tek TDS784D. I didn't have a lot of chance to set things up precisely. I stole five minutes when it wasn't being used and I was getting pushed out even then.

How many volts/div was the display set for ?

Thanks.

Heh.. I just noticed some more bugs:

• The grid lines are drawn incorrectly. The horizontal dotted lines have the usual four dots (five sub-divisions) per division, but the vertical grid lines have *five* dots (six sub-divisions) per division..
  
  Makes the mental arithmetic slightly more challenging, that!

• The Quick Measurement functions include an Average voltage display. Except it actually measures something more like average peak rather than plain average. Maybe the firmware guys also got confused by the six sub-divisions when testing their code..

Cheers

Correction: That scope above has only 60Mhz bandwidth, not 100Mhz.

Whoops. Forgot about that part. Here are some more images, both with the 1kHz test signal.

Okay, so they're not that much different at similar settings.

Thanks, Bitt!

Also keep in mind that the one I tested on is like a $30k oscilloscope.

That is SCARILY close to copying the Agilent MSO range's UI, button layout, labeling and screen format...

Hugo

Yeah, but beauty is only skin deep in this case.

Wow, I haven't seen one of those, this is a good hi-res pic and yes it is basically a direct knock-off:

http://www.meilhaus.de/presse/0907_dsomso6000a.jpg

Wow.. there are just so many firmware bugs, that I've now created a web page just to help track them. And since there is no other third-party info available on these products, it may as well be a review page.

My Welec W2022A Review is now up.

Nothing much new that hasn't already been posted here, but now it's collected into an easier to indigest form.

For some odd reason, the Wittig brothers are no longer responding to my emails.

Just for fun, today I downloaded the .flac version of YouScope and viewed it on the Welec W2022A scope.

After inverting channel-A, and adjusting various other controls, it produced a recognizable display, albeit at only 3 frames/sec.

Cool.

That Youscope thing is pretty cool but then an (analogue) CRO is really just a specialised TV... I would never expect a digital scope to do that good of a job of something like that. 3fps though ain't gonna help. That's where analogue scopes still have it to some extent although newer DSOs are trying to bridge that gap.

We actually had to build a complete video generator (reading an image from RAM using a primitive drawing program) and outputting XY back when I was at uni. Was a good practical.

Thanks for your review work Mark.

Here are a couple other bugs that you may want to add to your growing list:-

1. Power on zero drift. If you turn on the unit and observe the zero level, you will find that it drifts quite a bit over time - probably due to the lack of thermal compensation.

2. The video triggering doesn't work at all.

3. Occasionally, the trigger will lose sync and you need to stop and start the capture again for it to re-acquire the trigger.

I have actually e-mail Eric Wittig, whom I was told was in-charge of the code development, about these bugs but have not seen any fixes as yet.

Daniel

Thanks. I have more or less just cut/pasted those into my web page review now.


Ah.. so there really are *three* guys, then: Michael (sales), Thomas (tech), and now Eric (firmware).

But as with many others before us, they generally seem to smile and then not actually fix anything.

Cheers

Are you sure that's not just the AC-coupling doing it's self-centering thing?

Cheers

In case you are interested in downloading sampled data (and maybe later controlling) the scope using Linux, you may want to have a look at some stuff about the W2022A at Google groups.

Regards,
Falk

I was just having a look at DSOs on ebay and came across the google group for these CROs. This post is interesting:

http://groups.google.com/group/welec-dso/browse_thread/thread/dd72e1ad1d08c430

link to file:
http://welec-dso.googlegroups.com/web/FW...i-BwrUzBGT2hOzg

A year on was it a good purchase Mark? They seem to have disappeared from ebay.

They're still on eBay, selling 4-channel versions of the hardware now. It seems that most folks are picking those up for around US$400 or so, which is an okay deal if a real scope is out of the question due to price ($1400 and up) or size (bulky old-style tube scopes).

I like this little beast, and it lives on the workbench and is used from time to time for simple stuff. It's not as buggy as it was originally (firmware got updated slightly last summer), but it's a toy when compared with a "real" / expensive version.

EDIT: For example, it was just fine for debugging the empeg I2C timing last fall (mostly used my logic analyzer there, though) -- no issues at all with that. Ditto for when I was last poking at the temperature sensor circuitry.

I don't regret the purchase at all -- definitely do need a scope here, and anything else (w/200Mhz) was/is simply too much money for here and the little use it does see. So perfect for the weekend hobbyist, but not for a day job.

Cheers

Oooh.. there was even an April Fools Day (joke) posting about these.. very funny, but no warnings for the humour-impaired!

I'm a bit confused. Sure it's a joke? Maybe that recent post is, but there are posts about the firmware back in July 2008:

http://groups.google.com/group/welec-dso/browse_thread/thread/56f3c673928f18fb#

The firmware was released. That is what the 3rd party stuff is based on. The april fool is that they're sponsoring development and have a big list of desirable features I guess...

Yeah. We've had the source code (incomprehensible) since last summer. There's even a beta release from (unfortunately) April 1 2009 of a rework of it (mostly incomplete at present).

The April Fools is the announcement I linked to, of a development contract to fix the existing firmware and sell updates for $300 to existing owners. Yeah, right.

But like I said.. no smilies, so certain nationalities might not get it, and might even think it's a real deal!

Cheers

These days, now that I'm working with OTA television antennas (hobby), I'm really wishing for a 1GHz scope, to cover UHF television frequencies..

And I suppose if I had that already, I'd want a 3GHz scope for WiFi and satellite. But then I'd want a 6GHz scope for 802.11A. And so on..

Understand the need for bigger, better, more. Whilst I'm looking at a machine for a day job, it's also for home and coming out of my pocket (though it would be a tax dedcution).

I did have a quick look at the firmware. What a shocker. Basically all in one file...

Okay, how's this for clarity:

At US$400, *delivered*, I think a 4-channel 200Mhz scope like this is a pretty good deal, and way cheaper than any alternatives. It's slow, has the odd bug here and there, but it really does work.

And it has a colour display, decent menuing system, and takes up practically no space at all on the workbench. If I didn't already have one, I'd jump at the current offers!

And the auto white-balance on the 40D seems to work rather well.
With my previous camera (20D), that photo would have had a blue-green tint!

Cheers

Oh, forgot to mention. I did use the scope again quite recently, to actually *measure* the velocity factor for some RG-59 coaxial cable.

I'm making coax-loop baluns for some TV antennas, and it's very important to know how fast signals pass through the coax.

The nice thing about a scope this quick (1gs/sec) is that it only takes a few metres of coax to have sufficient delay that it can be measured on the scope!

The coax I had on hand here measured as a VF of 0.80c, which is quite close to the oft posted ballpark figures for RG-59 on the web (which range around 0.78 to 0.82 or so), for foam-core stuff.

Cheers

This reminds me of something I've been meaning to ask the board's opinion about. I'll put it in another post shortly.

A lot has happened with these scopes of late. Last summer, the (horrible) source code for the firmware was released, and over this past winter/spring some German chaps have been fussing away at it.

The current "beta" release of fixes/enhancements, based on the original factory firmware, is actually rather good. I've installed it on my own scope here, and most of the old bugs vanished, while some new features (re)appeared.

The FFT functionality has returned with a vengence, though it's still not useful beyond really low frequencies, and the scope is definitely a lot better behaved now.

The best thing with the new firmware though, is they've figured out how to reduce the inherent noise in the measurements, to perhaps half of what it used to be. This is good.

Related to that last point -- another person has been poking at the FPGA code, and determined that *all* of the visible noise is just the result of some firmware bugs. He's recoded some of the VHDL and posted youtube videos (search for welec) showing the difference. Quite astounding results, though it could be a long time before changes like that make it back in the new firmware releases.

Digging up an old thread.

We just bought a Rigol DS2000 series scope and it's brilliant. Because we're now doing a lot more analog stuff I find myself needing a lot more features out of the scope than I needed before and our old tektronix scope is just becoming more and more infurating to use!

We also bought a series 4000 function generator at the same time. We've needed a function generator for a while, I kept getting asked questions about our signal processing that I couldn't really answer without injecting known sets of signals into the front end, so hopefully I'll be able to give some definitive answers now.

Got to say that so far we're very impressed with the Rigol stuff.

Adrian

Has the state of the art in regards to osciliscope fronts ends for an iPad improved?

Is Oscium still the only player?

I don't need really high input bandwidth but I do need a large and high pixel display, hence the interest in using my own 'computer' for the user interface and display. And more than two analog input channels.

"Front ends"? From the looks of the photos on the Oscium main page, it looks like the iPad actually *is* the 'scope in some cases. The dongle has the test probes on it. That's kind of impressive. I didn't know anyone was doing that. Wow.

That's what I thought.

The scope (actually all the rigol equipment we bought) has usb and can be controlled with SCPI commands. This is particularly useful because 4 days out of 5 I'm hundreds of miles away from the physical scope and connected device. It's great to be able to remotely control it.

Same goes for the power supply, I can turn on/off channels set voltage & current limit etc.

And the multimeter, again I can set it into the mode I want and read back the readings etc.

So handy!

I had a good play with the scope yesterday and it's amazing for the price, not only does it feel physically solid (and expensive), the software doesn't seem flakey and it seems well thought out and comprehensive.

If only I could convince the wife that we needed one!

Adrian

When I looked at the Oscium it turned out it had no capture depth, ie it captured exactly one screenful, with no zooming possible. Not sure if that was just early software, but my dreams of pinch-zooming on a deep buffer died

Seems to still be the case

USB connected 'scopes' seem to be all over the low-end map, hard to figure out what is actually decent.

Well, many years later, and the Welec W2022A now has very usable third-party firmware, and a lot less noise on the signals. But I've decided to upgrade to a newer/better scope. There are now quite a few usable digital scopes with good bandwidth out there.

After a lot of reading/research, the perfectionists say to get something like a Lecroy scope, but those are horrifically expensive. In the budget category though, the Siglent brand is highly recommended. So I've ordered a 200Mhz 2-channel Siglent scope (1 gs/sec), for CAD$458+tax. The Lecroy 100MHz equivalent is more than 2X that price.

Real world reviews and measurements indicate the Siglent is the Real Deal, with actual 3dB bandwidth around 240MHz. The firmware for it has had regular updates and is working well.

Notice anything funny about the photos.. ?

The old Welec scope was imitating a more reputable Aligent's front panel, with totally different innards.

But in this case, Siglent actually designed the scope for Lecroy, but also sell it themselves! The two companies have quite a bit of their product lines "shared" like that.

It's displaying a waveform but there's nothing plugged into the probe connectors?

Two scopes, identical other than the Manufacturer's name at top left, and the considerably different price tags.

Scope arrived here today, and lives up to the reviews. Including the one on YouTube demonstrating a bug with the built-in UART decoder. A simple firmware downgrade took care of that bug, with no downsides I can see from the ChangeLog.

Cheers

I have not hunted for a ‘portable remote display/mobile app’ oscilloscope device in at least a year - has the situation improved?

Zoyi ZT-703S:

https://www.youtube.com/watch?v=kpzNVsSmUu0
https://www.aliexpress.us/item/1005006401570644.html

That's the state-of-the-art for cheap ones. Go 3X that price and they're pretty decent.

The EEVblog site is excellent for info about gear like this.

Also, the 4-channel version of the Siglent, the SDS1204X-E, can use either the built-in ethernet or a USB WiFi adapter, and has a built-in webserver which includes a mobile-optimized view.

EDIT: The new generation of DHO800/DHO900 Rigol scopes with touchscreens also have built-in web interfaces.